Cellular differentiation in a murine myelomonocytic leukemia.

Mouse peritoneal macrophages and macrophages derived from normal bone marrow progenitors in vitro possess surface receptors whose predominant specificity is directed toward the lgG2a subclass of lgG moleclues. Myelomonocytic leukemic cells also possess such lgG receptors but in an abnormally low frequency and without demonstrable subclass specificity. Within the leukemic population, monoblasts are distinguished from myeloblasts by their greater adhesiveness to glass, higher frequency of cells with surface receptors for lgG, and by erythrophagocytosis. Leukemic monoblasts, myeloblasts, and their morphologically mature progeny demonstrate impaired phagocytic ability. A concept of the development of surface receptors for lgG in the monocyte-macrophage cell line is presented.